Rim construction for pianos



June 6, 1939. w M. DAY 2,161,l39

RIM CONSTRUCTION F OOOOOOO S INVENTOR `Inne 6, 1939. wl M. DAY

RIM coNsTRUcTIoN Fon PIANos 2 Sheets-Sheet 2 Filed NOV. 26, 1937INVENTOR /,Lw 724.

Patented June 6, 1939 UNITED STATES PATENT OFFICE RIM CONSTRUCTION FORPIANOS Application November 26, 1937, Serial No. 176,410

8 Claims.

My invention has reference to piano construction and more particularlyto the construction of grand pianos of unusual shapes characterized bydiscontinuous rim curves and abrupt rim corners. They are in contrast tothe appearance of the conventional grand piano, and offer to thedecorative designer interesting possibilities for producing pianos ofunusual and pleasing appearances. They present, however, certainstructural problems.

One of these problems is that of constructing the piano rim. In the pastthe structural rims for grand pianos of unusual appearance have beenformed from a number of segments, gener- 16 ally of wood, each shaped toits appropriate segmental form, these segments being glued together inlap and butt joints. While such a method of construction provides agrand piano of a desired appearance, it fails to provide, per se, astrong 20 rim for the instrument. For, it is not entirely successfulunder the conditions of mechanical stress resulting from the flfteen totwenty tons of cumulative string tension in a modern piano, requiringthus additional bracing. Then, being 25 comprised of variousdiscontinuous glued joints, it is not entirely free from joint partingunder varying conditions of weather. It is to be compared with thestructural rim (variously called inner rim, soundboard rim, or acousticrim) of 30 the usual grand piano. There the structural rim is composedof a series of continuous laminae glued continuousy to form a strongunit in a complex but unbroken curve, requiring large radii of curvaturebut possessing both structural 35 and acoustic advantages.

It is therefore an object of my invention to provide a rim constructionfor pianos which retains the advantages of the usual grand piano rim butwhich is readily susceptible to external 40 modifications.

It is another object of the invention to provide an exemplary grandpiano of symmetrical appearance having a type of corner construction inkeeping with the first object and having the fundamental advantages of alarge soundboard area for its size and a strong, economical rim.

These objects and other objects which will be apparent to those skilledin the art on reading this specification, I accomplish by constructionsand arrangements of parts which I shall now describe in detail. Forclearance reference is had to the drawings wherein Figure 1 is a planview of a symmetrical grand 55 piano constructed according to theprinciples of the invention, the lid being removed and the piano cutaway partly to expose the rim;

Figure 2 is an elevational view of an exterior corner of the piano, asif viewed in a direction indicated by A in Figure l; 5

Figure 3 is a cross-section of a corner, taken on the cutting plane B-Bof Figure 1;

Figure 4 is an enlarged plan view of a corner with the top surfaceveneer removed from the outer rim and corner block; and 10 Figure 5 isan enlarged plan view of a modified form of corner, likewise with thetop surface veneer removed from the outer rim and corner block.

With reference now in particular to Figure l, a symmetrical grand pianocomprises an inner or structural rim I of continuous wood laminationsformed symmetrically with four corners each of large radii of curvature.Glued to the upper surface of the rim is a soundboard 2. On top of thesoundboard is placed a metal string-plate 3 securely attached to the rimI by screws as 4 extending through the soundboard into the rim. Theplate 3 supports strings 5, 5' attached to the soundboard throughbridges 6, 6'; and the piano contains awell-known pinblock and actionparts (not shown). It will be noted that by reason of its Shape thepiano is of large soundboard area.

Enclosing the inner rim and attaehed thereto except at the corners is anouter rim 'I of lesser thickness than the inner rim I and composedlikewise of continuous wood laminations. Since the rim 1 is of lesserthickness than rim I, its radii at the four corners, shown and abovementioned, may be smaller than those of the rim I; and thus moresusceptible for the exterior addition of narrow conforming corner blocks8 having sharp exterior corners. Between the two rims at the corners arewood filler blocks as 9. 40

It will be noted that the string-plate 3 extends into the four cornersto be adjacent the outer rim 'I and to cover the filler blocks 9(Figures 1 and 3). Moreover, the outer rim extends above the inner rimto form a casing for the piano (Figures 2 and 3).

A modified corner construction is shown in Figure 5. Here a corner block8' and outer rim 'I are overlaid with a surface veneer Ifl.

Having thus described my invention, I claim:

1. A grand piano case including a support rim and a closure rimenccnipassing said support rim, each of said rims comprising a pluralityof wood laminae respectively of the rim width, cemented together to formthe rim thickness and extending in length as a horizontal compound curvecomprising curve portions of relatively small curvature interspaced withcurve segments of relatively large outward convexity, said closure rimconforming to said support rim in said portions of relatively smallcurvature and secured thereto in said portions, said closure rim beingof lesser thickness than said support rim and of greater outwardconvexity in said convex segments, whereby in said segments said closurerim is spaced apart outwardly from said support rim, and a plurality ofWood corner members secured to the outer surface of said closure rimrespectively at said convex portions, said members extending each thewidth of said closure rim and conforming to said closure rim in theirsurfaces of junction therewith, the exposed surfaces of said membersforming tangential continuations of said closure rim portions of smallcurvature, Whereby said members present line corners extending the widthof said closure rim.

2. The structure as set forth in claim 1, including a plurality of Woodfiller blocks respectively in the spaces between corresponding said rimconvex portions and secured to said rims, said blocks conforming inshape respectively to the spaces between corresponding said portions tofill said spaces.

3. The structure as set forth in claim 1, including a plurality of WoodVeneer sheets secured to the exposed surfaces of said closure rim andsaid corner members, said sheets being respectively of the width of saidrim and said members and abutting end to end to cover effectively saidrim and said members.

4. The structure as set forth in claim 1, including a plurality of Woodfiller blocks in the spaces between corresponding said rim convexportions and secured to said rims, said blocks conforming in shaperespectively to the spaces between corresponding said portions to fillsaid spaces, and a plurality of Wood veneer sheets secured to theeXposed surfaces of said closure rim and said corner members, saidsheets being respectively of the width of said rim and said members andabutting end to end to cover effectively said rim and said members.

5. A symmetrical grand piano case including a support rim and a closurerim encompassing said support rim, each of said rims comprising aplurality of Wood laminae respectively of the rim width, cementedtogether to form the rim thickness and extending in length as ahorizontal compound curve comprising two end portions of similar shape,a middle portion symmetrically disposed with respect to said endportions, and two intermediate portions of similar shape extendingrespectively from adjacent an inner end of an end portion to adjacent anend of said middle portion, said portions being of relatively smallcurvature and interspaced With segments of relatively large outwardconvexity, said closure rim conforming to said support rim in saidportions of relatively small curvature and secured thereto in saidportions, said closure rim being of lesser thickness than said supportrim and of greater outward convexity in said convex segments, whereby insaid segments said closure rim is spaced apart outwardly from saidsupport rim, and a plurality of Wood corner members secured to the outersurface of said closure rim respectively at said convex portions, saidmembers extending each the width of said closure rim and conforming tosaid closure rim in their surfaces of junction therewith, the exposedsurfaces of said members forming tangential continuations of saidclosure rim portions of small curvature, whereby said members presentline corners extending the width of said closure rim.

6. The structure as set fortli in claim 5, including a plurality of Woodfiller blocks respectively in the spaces between corresponding said rimconvex portions and secured to said rims, said blocks conforming inshape respectively to the spaces between corresponding said portions, tofill said spaces.

7. The structure as set forth in claim 5, including a plurality of Woodveneer sheets se-- cured to the exposed surfaces of said closure rim andsaid corner members, said sheets being respectively of the width of saidrim and said members and abutting end to end to cover eiiectively saidrim and said members.

8. The structure as set forth in claim 5, including a plurality of WoodVeneer sheets secured to the exposed surfaces of said closure rim andsaid corner members, said sheets being respectively of the width of saidrim and said members and abutting end to end to cover eifectively saidrim and said members, and a plurality of Wood filler blocks respectivelyin the spaces between corresponding said rim convex portions and securedto said rims, said blocks conforming in shape respectively to the spacesbetween corresponding said portions, to fill said spaces.

WILBR M. DAY.

